commit e2a9eeb69f upstream.
syzbot and Eulgyu Kim reported crashes in mptcp_pm_nl_get_local_id()
and/or mptcp_pm_nl_is_backup()
Root cause is list_splice_init() in mptcp_pm_nl_flush_addrs_doit()
which is not RCU ready.
list_splice_init_rcu() can not be called here while holding pernet->lock
spinlock.
Many thanks to Eulgyu Kim for providing a repro and testing our patches.
Fixes: 141694df65 ("mptcp: remove address when netlink flushes addrs")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot+5498a510ff9de39d37da@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/6970a46d.a00a0220.3ad28e.5cf0.GAE@google.com/T/
Reported-by: Eulgyu Kim <eulgyukim@snu.ac.kr>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/611
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260124-net-mptcp-race_nl_flush_addrs-v3-1-b2dc1b613e9d@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Conflicts because the code has been moved from pm_netlink.c to
pm_kernel.c later on in commit 8617e85e04 ("mptcp: pm: split
in-kernel PM specific code"). The same modifications can be applied
in pm_netlink.c with one exception, because 'pernet->local_addr_list'
has been renamed to 'pernet->endp_list' in commit 35e71e43a5
("mptcp: pm: in-kernel: rename 'local_addr_list' to 'endp_list'"). The
previous name is then still being used in this version.
Also, another conflict is caused by commit 7bcf4d8022 ("mptcp: pm:
rename helpers linked to 'flush'") which is not in this version:
mptcp_nl_remove_addrs_list() has been renamed to
mptcp_nl_flush_addrs_list(). The previous name has then been kept. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
338d40bab2